BCH403 PRACTICE TEST QUESTIONS
WITH CERTIFIED ANSWERS
E1: Which of the following statements is true regarding the hydrophobic effect? -
Answer-Non - Polar molecules are driven together in order to maximize the entropy of
water.
E1: The peptide in question 17 is dissolved into a solution that has a pH of 6.5. Under
these conditions the net charge of the peptide is - Answer-+1
E1: A glycine residue is disruptive to the stability of an a-helix or a b-strand because: -
Answer-It's R-group is too small to participate in stabilizing interactions with neighboring
R - groups
E1: With a pKa of 6.37 the carbonic acid/bicarbonate system serves to buffer changes
to the pH of blood. The acid dissociates as follows:
H2CO3 + H20 <-> HCO3- + H30+
If a solution of 0.5M carbonic acid is adjusted to a pH of 2.5, the primary form of the
buffer will be: - Answer-H2CO3
E1: Most nonpolar residues are located on the interior of a protein fold, but are
occasionally found on surfaces where they can mediate protein interactions. The
molecular basis of a hypothetical infectious disease is that a bacterial protein interacts
with a human protein by sharing a nonpolar surface. Your goal as a researcher is to find
a way to disrupt this interaction. Which of the following surface mutations are most likely
to disrupt the protein interactions? - Answer-Leucine --> Glutamine
E1: You've discovered a new species of rodent living at a very high altitude, where the
partial pressure of oxygen is low. What would you predict regarding the oxygen binding
capacity of this new species? - Answer-B and D ( it's hemoglobin will have a very low
P50 value & the primary amino acid sequence of its hemoglobin will not be identical to
that of a species living in an oxygen rich atmosphere)
E1: the following peptide is composed of which amino acid sequence
[Picture of sequence. May insert later] - Answer-LKQIFKDIWTIGW
E1: The following sequence of 16 residues represents an Alpha helical stretch in an
enzyme from the bacterium that causes tuberculosis. which of the following is not true
regarding the structure of this Alpha Helix?
, QFLRDTANSLLDNLIT - Answer-Mutation from the phenylalanine residue to a proline
will prevent the rest of the sequence from forming an Alpha Helix.
E1: The residue sequence of a fibrous protein is shown below. which protein does this
sequence likely correspond to?
MGISQKLYRDVNNAFQSRINYWLS - Answer-fibroin
E1: Which of the following is true regarding oxygen binding to one molecule of
myoglobin? - Answer-B and C (A histidine is required to hydrogen bond with the bound
oxygen thus stabilizing it. & the iron atom is located outside the plane of the heme when
oxygen is not bound)
E1: A chromatography column was used to try to purify a protein that is 10 kilodaltons in
size. Some of the illusion fractions were run on SDS page and are shown below, with
the lower numbered fractions eluting first period based only on this information, what
kind of chromatographic column was used it was the attempt successful? The charges
on the gel are shown on the left.
[May insert picture later] - Answer-Nickel affinity, and it did work
E1: Your goal is to separate a mixture of the two polypeptides shown below, and obtain
purified peptide one for further study as a neurotransmitter. which purification technique
would be most effective and why?
Peptide 1: MHTRRAPLQAWKKPRADHVL
Peptide 2: MHTDEAPLQAWKDPEADHVLW - Answer-Cation exchange, since peptide 1
is more positively charged and will "stick" to that resin best.
E1: Ascorbate (Vitamin C) is an important part of any diet because: - Answer-It is
utilized by the enzyme lysyl oxidase, which crosslinks lysine residues to stabilize the
structure of tropocollagen.
E1: Why do proteins fold? - Answer-A and B are correct (It is entropically favorable for
water & It is enthalpically favorable for the protein)
E1: The structural changes in hemoglobin that contribute toward its positive
cooperativity for oxygen consist of: - Answer-All of the above ( movement of iron into the
plane of the heme & movement of a neighboring veiling residue due to strain from
changes in the heme & the breaking of a covalent bond with the regulatory molecule
BPG
E1: The following oxygen binding curves are derived from independent experiments.
which of the following statements is not true regarding these plots?
WITH CERTIFIED ANSWERS
E1: Which of the following statements is true regarding the hydrophobic effect? -
Answer-Non - Polar molecules are driven together in order to maximize the entropy of
water.
E1: The peptide in question 17 is dissolved into a solution that has a pH of 6.5. Under
these conditions the net charge of the peptide is - Answer-+1
E1: A glycine residue is disruptive to the stability of an a-helix or a b-strand because: -
Answer-It's R-group is too small to participate in stabilizing interactions with neighboring
R - groups
E1: With a pKa of 6.37 the carbonic acid/bicarbonate system serves to buffer changes
to the pH of blood. The acid dissociates as follows:
H2CO3 + H20 <-> HCO3- + H30+
If a solution of 0.5M carbonic acid is adjusted to a pH of 2.5, the primary form of the
buffer will be: - Answer-H2CO3
E1: Most nonpolar residues are located on the interior of a protein fold, but are
occasionally found on surfaces where they can mediate protein interactions. The
molecular basis of a hypothetical infectious disease is that a bacterial protein interacts
with a human protein by sharing a nonpolar surface. Your goal as a researcher is to find
a way to disrupt this interaction. Which of the following surface mutations are most likely
to disrupt the protein interactions? - Answer-Leucine --> Glutamine
E1: You've discovered a new species of rodent living at a very high altitude, where the
partial pressure of oxygen is low. What would you predict regarding the oxygen binding
capacity of this new species? - Answer-B and D ( it's hemoglobin will have a very low
P50 value & the primary amino acid sequence of its hemoglobin will not be identical to
that of a species living in an oxygen rich atmosphere)
E1: the following peptide is composed of which amino acid sequence
[Picture of sequence. May insert later] - Answer-LKQIFKDIWTIGW
E1: The following sequence of 16 residues represents an Alpha helical stretch in an
enzyme from the bacterium that causes tuberculosis. which of the following is not true
regarding the structure of this Alpha Helix?
, QFLRDTANSLLDNLIT - Answer-Mutation from the phenylalanine residue to a proline
will prevent the rest of the sequence from forming an Alpha Helix.
E1: The residue sequence of a fibrous protein is shown below. which protein does this
sequence likely correspond to?
MGISQKLYRDVNNAFQSRINYWLS - Answer-fibroin
E1: Which of the following is true regarding oxygen binding to one molecule of
myoglobin? - Answer-B and C (A histidine is required to hydrogen bond with the bound
oxygen thus stabilizing it. & the iron atom is located outside the plane of the heme when
oxygen is not bound)
E1: A chromatography column was used to try to purify a protein that is 10 kilodaltons in
size. Some of the illusion fractions were run on SDS page and are shown below, with
the lower numbered fractions eluting first period based only on this information, what
kind of chromatographic column was used it was the attempt successful? The charges
on the gel are shown on the left.
[May insert picture later] - Answer-Nickel affinity, and it did work
E1: Your goal is to separate a mixture of the two polypeptides shown below, and obtain
purified peptide one for further study as a neurotransmitter. which purification technique
would be most effective and why?
Peptide 1: MHTRRAPLQAWKKPRADHVL
Peptide 2: MHTDEAPLQAWKDPEADHVLW - Answer-Cation exchange, since peptide 1
is more positively charged and will "stick" to that resin best.
E1: Ascorbate (Vitamin C) is an important part of any diet because: - Answer-It is
utilized by the enzyme lysyl oxidase, which crosslinks lysine residues to stabilize the
structure of tropocollagen.
E1: Why do proteins fold? - Answer-A and B are correct (It is entropically favorable for
water & It is enthalpically favorable for the protein)
E1: The structural changes in hemoglobin that contribute toward its positive
cooperativity for oxygen consist of: - Answer-All of the above ( movement of iron into the
plane of the heme & movement of a neighboring veiling residue due to strain from
changes in the heme & the breaking of a covalent bond with the regulatory molecule
BPG
E1: The following oxygen binding curves are derived from independent experiments.
which of the following statements is not true regarding these plots?
